1. Field of the Invention
An embodiment of the present invention relates to a structure of a photoelectric conversion device utilizing photoelectric effect of a semiconductor and a manufacturing method thereof.
2. Description of the Related Art
A photoelectric conversion device in which a photoelectric conversion cell formed using a single crystal semiconductor and a photoelectric conversion cell formed using an amorphous semiconductor are combined is known. For example, a tandem photoelectric conversion device is disclosed, which is formed as follow: a p-type single crystal silicon layer separated from a p-type single crystal silicon substrate is bonded to a substrate; and an n-type single crystal silicon layer, a p-type amorphous silicon layer, and an n-type amorphous silicon layer are formed in this manner over the p-type single crystal silicon layer (see Patent Document 1).
On the other hand, a single-type photoelectric conversion device is disclosed, which is formed as follow: a microcrystalline silicon layer having sensitivity to a long wavelength and an amorphous silicon layer having sensitivity to a short wavelength are stacked to form an i-type semiconductor layer, and the i-type semiconductor layer is interposed between a p-type semiconductor layer and an n-type semiconductor layer (see Patent Document 2).
The two kinds of photoelectric conversion devices exemplified above have different structures; however, objects of both the structures are to improve conversion efficiency by utilizing characteristics of amorphous silicon whose light absorption coefficient is high in the range of visible light and characteristics of single crystal silicon whose light absorption coefficient is higher in the range of light having long wavelength and whose life time of minority carriers is longer, as compared to amorphous silicon.